Hannover 2010 – wissenschaftliches Programm
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MO: Fachverband Molekülphysik
MO 3: Theory: Quantum Chemistry and Molecular Dynamics
MO 3.5: Vortrag
Montag, 8. März 2010, 17:45–18:00, F 102
Vibronic transitions and quantum dynamics in molecular oligomers: a theoretical analysis with an application to aggregates of perylene bisimides — •Volker Engel1, Joachim Seibt1, Theresa Winkler1, Klaus Renziehausen1, Volker Dehm2, Frank Würthner2, and Hans-Dieter Meyer3 — 1Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 2Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg — 3Theoretische Chemie, Universität Heidelberg, Im Neuenheimer Feld 229, 69120 Heidelberg
Vibronic absorption spectra of molecular aggregates consisting of up to N = 9 monomer units are calculated employing methods of time-dependent quantum mechanics. Taking one vibrational degree of freedom for each monomer into account and treating one-exciton excited electronic states, this leads to a problem with N vibrations and N electronically coupled states. The demanding quantum propagation is carried out within the MCTDH (Multi-Configuration Time-Depended Hartree) method. Spectral features of and population transfer in the aggregates are analyzed as a function of the aggregate size and the strength of the electronic coupling. Employing a model for oligomers of perylene bisimides it is shown how measured temperature-dependent absorption spectra correlate with the aggregate size. Furthermore, the exciton localization and dynamics in these aggregates is investigated.